Federline's reaction came after he saw the pictures of Beyonce, 34, and husband Jay Z taken during Canelo vs Cotto boxing match in Las Vegas on Saturday, reported Us magazine.
"She looked botoxed," Federline, 37, tweeted at the blogs account.
"So sad when a beautiful woman chops and screws her face up with Botox and surgery," he followed up.
Various fans people lashed back at Federline for his comments, saying that he was just trying to create publicity for himself.